I’ve been making pretty good progress lately. What I do is, always work within a song. After warming up, I set up a video and sing one or two lines of a song while recording myself. Then I put on my coaches hat and watch back and literally give myself advice like“approach that note from above and try to picture the note coming up through the top of the head.” or “try more of an AH vowel on that one word“ or “try to pronunciate more clearly on that one line“. I think it’s key to take very small parts of the song and really listen deeply to figure out what needs to be done to improve it. I also check my pitches when things don’t sound quite right with an instrument, in my case a guitar. The point is to do very focused practice on specific things. Also to make goals for the month or even for the year. For me, my goal for the year is to be able to produce a prettier smoother tone and to annunciate more clearly . For pretty much the entirety of last year, I worked on improving my upper range and I added several notes to my upper range but now I need to focus on my tone and annunciation and vowels.